The invention relates to cylinders having inclined grooves on the periphery thereof for paying off yarn from a textile machine onto an adjacent take-up bobbin that is frictionally coupled to the cylinder.
Conventionally, yarn exiting from the spinning chamber of an open-end spinning machine is received by a helical or other inclined groove on the surface of the distributing cylinder, which pays off the yarn across the surface of the bobbin in interleaved-spool fashion when the cylinder is rotated. During the rotation of the cylinder, frictional engagement maintained between the adjacent peripheries of the cylinder and the bobbin cause the bobbin to rotate so that the yarn is evenly distributed thereon.
In known designs of this type, the required frictional driving engagement between the cylinder and the bobbin is effected by roughening the peripheral surface of the cylinder. Such arrangements have several disadvantages, particularly during high-speed operation of the spinning machine. For example, because of the roughened periphery adjacent the cylinder grooves, the yarn exiting from the grooves toward the bobbin is susceptible to tearing and other damage.
In addition, the roughening of the cylinder surface has been found to effect a variation in yarn tension at different points along the path of of distribution of the yarn. As a result, either the yarn is subject to local slackening, or, if such slackening is compensated, other portions of the yarn are subjected to excess tension and strain.
Furthermore, the roughness of the surface of the cylinder in such designs tends to gradually diminish with time by abrasion and the like, thereby causing a corresponding loss in frictional driving torque on the driven take-up bobbin.